I was using Musescore, and I got an ad for some thing called "Cantai". After looking into it, it's kinda like SynthV, but working directly in Musescore! It works by taking the notes and lyrics you lay down in the score editor and singing them. It's $14.99 US per month, or a one-time purchase of $299 US. However, it has a limit of 180 minutes of audio rendering per week. More info is available in the link below.
